Air springs are used to cushion two vehicle parts that can move relative to one another, but also to modify the level of a vehicle. Typical air springs have an air-filled air spring bellows made of rubber, which is closed airtightly by means of an upper closure element and a rolling piston. The closure element and the rolling piston are also referred to as air spring components. When subjected to a load, the air spring bellows rolls along the outer surface of the rolling piston. The rolling piston is furthermore used to attach the air spring to a vehicle part.
The spring action of air springs is based on the compressibility of air. Thus, the spring hardness is dependent on the volume of the enclosed air and the pressure thereof. The level can be set by changing the air quantity.
The properties of the air spring can be improved by enlarging the available volume. An enlargement of the volume can generally be achieved by making the air spring components of a corresponding size. Since the available installation space for the air spring components is often very restricted, they must often be embodied in several parts to make good use of the volume.
Moreover, multi-part configuration of the air spring components is necessary simply for manufacturing reasons. This is because air spring components are nowadays generally produced from plastic by injection molding or centrifugal molding for reasons of weight and cost. To increase the rigidity and load bearing capacity of a rolling piston manufactured from plastic, however, internal reinforcing ribs are often required. In the case of air spring components produced as a single part, the reentrant angles formed in this case make removal from the mold completely impossible in most cases, or possible only with difficulty. A multi-part configuration of the air spring component is therefore required.
However, a two-part or multi-part configuration has the disadvantage that special design measures must be taken for sealing and for connecting the individual parts in a manner which prevents loss. In particular, care must be taken to ensure that there is adequate leaktightness at the joint between the two individual parts in order to ensure correct operation of the air spring.